I ssh'd into the machine and started the app but I get an error
saying "Cannot connect to X server" ..

Well, both ends of the ssh suite have to allow X Forwarding.

Hmm, well, this depends on how Nirmal wants to connect to the local X
server..
He either could set the $DISPLAY on the remote machine to
local.hosts.ip.address:0.0 which should (companied by a xhost +) do the
trick in most cases, or, because the former doesn't make /much/ sense
when useing ssh, he could enable X11 forwarding through the ssh
connection, which is neat, 'cause encrypted..

lg,

daniel, just to show up the 2nd possibility (Which also works without
root access to the remote machine, if X11forwarding is disabled in
sshd_config.)

PS: Sorry Rogério, for sending this "twice" to you, I'm just to stupid
to respond to a List mail correctly the first time.. :o/